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07:37
TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method
Published on: April 26, 2017
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Instability of hydrogenated TiO2.
Manjula I Nandasiri1, Vaithiyalingam Shutthanandan1, Sandeep Manandhar1
1Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , PO Box 999 MS K8-93, Richland, Washington 99352, United States.
The Journal of Physical Chemistry Letters
|November 8, 2015
Summary
Hydrogenated titanium dioxide (H-TiO2) shows poor thermal stability. Hydrogen easily diffuses out of the material at low temperatures, limiting its use as a visible light photocatalyst.
Area of Science:
- Materials Science
- Surface Science
- Photocatalysis
Background:
- Hydrogenated titanium dioxide (H-TiO2) is proposed as a promising visible light photocatalyst.
- Understanding the thermal stability of hydrogen within TiO2 is crucial for its practical application.
Purpose of the Study:
- To systematically investigate the thermal stability of hydrogen in rutile TiO2.
- To determine the hydrogen diffusion behavior and surface reduction effects upon annealing.
Main Methods:
- Proton implantation into rutile TiO2(110) crystals.
- Nuclear Reaction Analysis (NRA) to profile hydrogen distribution.
- Rutherford Backscattering Spectrometry (RBS) for elemental analysis.
- Ultraviolet and X-ray Photoelectron Spectroscopy (UPS/XPS) for surface electronic state analysis.
Main Results:
- Annealing at 373 K caused hydrogen profiles to broaden towards the surface.
- Hydrogen completely diffused out of the crystal into vacuum by 473 K.
- Surface reduction was observed concurrently with hydrogen diffusion, unlike in pristine TiO2.
Conclusions:
- Hydrogen exhibits facile bulk diffusivity in rutile TiO2 at low temperatures.
- The observed interfacial activity and rapid hydrogen out-diffusion limit the long-term stability and photocatalytic potential of H-TiO2.
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